Fraternal twins are the product of two eggs and two sperm cells. Although extremely rare, a set of fraternal twins can have two different fathers. Sperm cells can live in a woman’s body for 4 to 5 days. Once an ovary releases, an egg cell remains viable for 12 to 48 hours. Should a woman have sexual relations with more than one man during this fertile period and release two egg cells while she is ovulating, she could become pregnant with fraternal twins who have two different fathers.
There are cases where assisted fertility methods, such as in vitro fertilization (IVF), can produce fraternal twins with different fathers. Should the sperm sample used in an IVF case inadvertently contain a mixture of different donors’ sperm, any resulting zygotes could have different fathers. While this is a rare occurrence, it has happened.
For this reason, we recommend that both fraternal twins involved in a paternity case be tested against the alleged father. Unlike fraternal twins, identical twins cannot have two different fathers, as identical twins are the product of one egg and one sperm cell whose zygote splits early in their development. Since only one zygote was formed in fertilization, only one man can be the father.
TWIN ZYGOSITY TESTING
In addition to DNA paternity testing of twins, a twin zygosity test can also be performed. The results will reveal whether a set of twins are fraternal or identical. Usually, when twins are born, the physician can tell whether twins are identical or fraternal by examining the placenta. Identical twins usually share a placenta, while fraternal twins are usually in two different placentas. Fraternal twins will NOT have exactly the same DNA, although like other siblings, they will share some of the DNA they inherit from both parents. Identical twins will have the exact same DNA.
If there is doubt about the twin zygosity that was determined at the time of birth, a DNA test will reveal the truth. A twin zygosity test compares the twins’ DNA profiles to see whether they are a match. If they are an exact match it proves they are identical.
Reach out to AccurateScreens.com with your questions related to testing twins.